[Python-Dev] Rationale for sum()'s design?

Greg Ewing greg.ewing at canterbury.ac.nz
Thu Mar 17 02:34:23 CET 2005

John Williams wrote:
> Michael Walter wrote:
>> Would this _syntax_ work with generic types:
>>   def sum(seq: sequence[T], initial: T = T()) -> T.
> This doesn't make sense with existing semantics because default 
> arguments are evaluated when the function is defined, but T() can't be 
> evaluated until the function is called.

Not to mention that if the seq is empty, there's no
way of knowing what T to instantiate...

Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury,	   | A citizen of NewZealandCorp, a	  |
Christchurch, New Zealand	   | wholly-owned subsidiary of USA Inc.  |
greg.ewing at canterbury.ac.nz	   +--------------------------------------+

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